FeSO₄ (iron(II) sulfate) is a solid at room temperature and standard pressure.

Here's why:

* Ionic Compound: FeSO₄ is an ionic compound, meaning it's composed of positively charged ions (Fe²⁺) and negatively charged ions (SO₄²⁻).

* Strong Electrostatic Forces: These ions are held together by strong electrostatic forces, creating a rigid, crystalline structure.

* High Melting Point: To break these bonds and transition to a liquid state, a significant amount of energy is required, resulting in a high melting point.

Therefore, FeSO₄ exists as a solid under typical conditions.